A Subscriber Identity Module (SIM) card is a removable circuit card for use in wireless communication devices, which stores authentication data and information identifying the device to a mobile network. A SIM card, though, allows access to only one wireless network operator. In other words, the SIM card is “locked” to one operator, and to access another wireless network operator the device user must replace the current SIM card with a SIM card configured for that other operator.
An Embedded Universal Integrated Circuit Card (eUICC) differs from a SIM in that it is not removable, and instead can be reconfigured or “provisioned” to allow access to different wireless network operators.
Architectures and functionalities of eUICCs are set forth in GSMA Embedded SIM Solution Specification, GSMA Embedded SIM Remote Provisioning Architecture, Version 1.1, 17 (December 2013), the disclosure of which is hereby incorporated herein in its entirety by reference.